There are no authenticated reports of hybrids between tigers and jaguars. Such hybrids could only occur in zoos as the animals occupy different continents.

There is a claimed sighting of a lion x black jaguar cross (male) and a tiger x black jaguar cross (female) loose in Maui, Hawaii. There are no authenticated tiger/jaguar hybrids and the description matches that of a liger. The alleged tiger x black jaguar was large, relatively long necked (probably due to lack of a ruff or mane) with both stripes and "jaguar-like" rosettes on its sides. The assertion of hybrid identity was due to the combination of black, dark brown, light brown, dark orange, dark yellow and beige markings and the tiger-like stripes radiating from its face. It is more likely to have been a released liger since these are very large and have a mix of rosettes (lion juvenile markings) and stripes and can have a brindled mix of colours exactly as described (their markings are extremely variable).

REFERENCES AND FURTHER READING

For more information on the genetics of colour and pattern:
Robinson's Genetics for Cat Breeders & Veterinarians 4^th Ed (the current version)

For more information on genetics, inheritance and gene pools see:
The Pros and Cons of Inbreeding
The Pros and Cons of Cloning

For more information on anomalous colour and pattern forms in big cats see
Karl Shuker's "Mystery Cats of the World" (Robert Hale: London, 1989 - some of the genetics content is outdated)